The following description of the background of the invention is provided simply as an aid in understanding the invention and is not admitted to describe or constitute prior art to the invention.
The kisspeptin-54 peptide is essential for sexual reproduction and it suppresses cancer metastasis. It is also known as metastin, kisspeptin 1-54, KP-54, and KiSS-1 (68-121). Kisspeptin-54 is the carboxamide fragment of residues 68-121 of the protein KiSS-1, which in turn is encoded by the KiSS-1 gene. Kisspeptin-54 potently and selectively stimulates the G-protein-coupled receptor 54 (GPR54) to signal secretion of gonadotropin-releasing hormone (GnRH). Rhythmical secretions of GnRH initiate puberty, coordinate ovulation, and maintain overall reproductive function. Kisspeptin-54 is known to suppress the progression of melanomas and breast cancers. It is postulated that kisspeptin-54 suppresses metastasis by inhibiting chemotaxis and invasion of cancer cells.
Human kisspeptin-54 (CAS No: [374683-24-6]) consists of 54 amino acids with a molecular weight of about 5857.5 g/mol and a monoisotopic mass of about 5854.0 g/mol. It is a peptide amide cleavage product containing the amino acid residues from 68 to 121 of the 138 amino acid KiSS-1 protein. Other bioactive peptides that result from cleavage of KiSS-1 are kisspeptin-14 (KP-14, 41-54), kisspeptin-13 (KP-13, residues 42-54), and kisspeptin-10 (KP-10; residues 45-54).
Kisspeptin-54 has been identified using tandem mass spectrometry. See e.g., Kotani, M., et al., J. Biol. Chem. 2001, 276(37), 34631-6 (isolated); Dhillo, W., et al., J. Clin Endocrinol. Metab. 2005, 90(12), 6609-15 (synthetic). Kisspeptin-54 has been quantitated using immunoassays. See e.g., Jayasena et al., J. Endocrinol. Metab. 2009, 94(11), 4315-23 (measured immunoreactivity of antibody with kisspeptin-54). Among the kisspeptin peptides, only kisspeptin-10 has been reported to be purified for and subjected to quantitative mass spectrometry. Chan et al., J. Clin. Endocrinol. Metab., 2011, 96(6), E908-15.